The purpose is to elicit molecular details of conformational kinetics in polypeptides and DNA. An eventual aim is to understand the mechanisms and pathways of DNA double helix formation, of protein folding, and of denaturation and renaturation. A mathematical model of the rates for passing between the various configurational states was previously formulated. Molecular states are determined by specification for each residue of a helical or random coil conformation. A comprehensive series of experiments on viral DNA indicated that the denaturation rates depend strictly upon the instantaneous conformational state, whereas the constant rates of renaturation depended only upon initial and final conditions. The simplest theoretical model yields qualitative agreement with the denaturation experiments and the series of renaturation experiments from the same initial condition. Partial agreement with the group of renaturation experiments with the same final condition is achieved only by including a bimolecular helix initiation step with properly matched pairs of strands. Comparison of all experimental and calculated rates yields 5x10 to the 4th power per min as the approximate step rate for melting a single base pair.